Mutant characterization and in vivo conditional repression identify aromatic amino acid biosynthesis to be essential for Aspergillus fumigatus virulence

Abstract

Pathogenicity of the saprobe Aspergillus fumigatus strictly depends on nutrient acquisition during infection, as fungal growth determines colonisation and invasion of a susceptible host. Primary metabolism has to be considered as a valid target for antimycotic therapy, based on the fact that several fungal anabolic pathways are not conserved in higher eukaryotes. To test whether fungal proliferation during invasive aspergillosis relies on endogenous biosynthesis of aromatic amino acids, defined auxotrophic mutants of A. fumigatus were generated and assessed for their infectious capacities in neutropenic mice and found to be strongly attenuated in virulence. Moreover, essentiality of the complete biosynthetic pathway could be demonstrated, corroborated by conditional gene expression in infected animals and inhibitor studies. This brief report not only validates the aromatic amino acid biosynthesis pathway of A. fumigatus to be a promising antifungal target but furthermore demonstrates feasibility of conditional gene expression in a murine infection model of aspergillosis.

Keywords:

• aspergillosis
• conditional promoter replacement
• glyphosate
• primary metabolism
• shikimate pathway
• Tet-ON

This article is referred to by:

In vivo veritas: Aspergillus fumigatus proliferation and pathogenesis – conditionally speaking

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

We thank Michaela Dümig for excellent technical assistance, Dr. Tina Schäfer for precious help, Prof. Dr. Christian Bogdan for critical review of the manuscript, and all other members of the departments for support and discussions.

Funding

This work was financially supported by the German Research Foundation (KR2294/1 and KR2294/3–1), the European Science Foundation by its Fuminomics Research Networking Program (06-RNP-132), the University of Würzburg, the Free State of Bavaria, the Microbiology Institute at the University Hospital of Erlangen, the University of Erlangen-Nürnberg (ELAN-12–08–17–1), as well as the German Federal Ministry of Education and Research (FKZ 031A408A) by funding the AspMetNet consortium during the first call of the Infect-ERA research co-ordination action.